If all OSPF routers in an area have the same priority and no loopback is configured, which address is used as the router ID?

When no loopback interface is configured and OSPF router priorities are equal, the router ID is determined by the highest IP address of any active physical interface on the router. This ensures a unique identifier for each router within the OSPF domain. The router ID is crucial for OSPF operations like neighbor establishment and SPF calculations. The IP address of the first Fast Ethernet interface or the lowest IP address among active interfaces are not the default selection criteria. The console management interface IP is irrelevant to OSPF router ID selection. The priority value is used in DR/BDR election, not as the router ID itself, and it doesn't become the router ID if a loopback is configured.